SDS100 Audio Muting Mid Transmission

[Linn]

I live in Fort Worth, but was in McKinney for a family event several days last week. I didn't take the time to create any favorites lists and just scanned from the database. I only listened from my hotel room near the intersection of 75 and 380 using my SDS200.

Before reading your post I was scanning multiple systems from the database including the Collin County System. There were no obvious drops or muting, but I was not listening specifically for that. After reading your posts I specifically listened to the Collin County system to see if I noticed a problem. I did not notice any audio muting over about 45 minutes of listening to the system Thursday night. The next morning I again listened specifically to the system for about 30 minutes and did not notice any audio muting. There were several times where I missed replies from field units to dispatch, but it sounded like it was cases where the dispatcher was still keyed up when the field unit responded. This commonly happened on the old Fort Worth smartnet system and was the way the system was designed so I figured that was what I was hearing.

From what I have read and the comments I also wonder if you are having some sort of interference issue.

 

[jmulvihill]

I live in Fort Worth, but was in McKinney for a family event several days last week. I didn't take the time to create any favorites lists and just scanned from the database. I only listened from my hotel room near the intersection of 75 and 380 using my SDS200.

Before reading your post I was scanning multiple systems from the database including the Collin County System. There were no obvious drops or muting, but I was not listening specifically for that. After reading your posts I specifically listened to the Collin County system to see if I noticed a problem. I did not notice any audio muting over about 45 minutes of listening to the system Thursday night. The next morning I again listened specifically to the system for about 30 minutes and did not notice any audio muting. There were several times where I missed replies from field units to dispatch, but it sounded like it was cases where the dispatcher was still keyed up when the field unit responded. This commonly happened on the old Fort Worth smartnet system and was the way the system was designed so I figured that was what I was hearing.

From what I have read and the comments I also wonder if you are having some sort of interference issue.

Thanks for the info Linn. At this point, I am not sure what is going on. Just not sure how interference would act the way that this is acting... I would expect static or some other noise in the transmission, but in this case, the scanner is muting. If someone at Uniden could outline how interference can engage an algorithm that mute the audio for 5 seconds, it would help me better grasp what is going on and why things are happening. It is just frustrating, but if this is the worst challenge I run in to today, then I am blessed... ;-)

 

[jmulvihill]

The high noise indicates an interfering signal. One of my beta testers happened to be in Collin County yesterday, and monitored the system with no issues, obviously from a different location.

AUTO simply sets modulation to whatever the default is for the band (which is NFM), so setting to NFM should only have a placebo effect.

I would try turning on attenuation, then retrying each filter setting. If you had an SDR dongle, you might be able to monitor a swath of spectrum and see when the offending signal appears (you'd see a spike on the spectrum monitor concurrent with the interference). Knowing where in the spectrum the signal is relative to the target frequency might open other possiblities. Or, you might be able to re-orient your antenna to minimize reception of the interfering signal.

Also, engineering noted that, since you are monitoring from an FL, you should confirm that all the channels are set for Analog (which would be the default if you moved the channels from the main database, but not if you programmed them by hand).

Well, I got me the RTL-SDR and have it setup now with SDR#. I am not seeing anything that jumps out at me, but have no real clue as to what to look for. On the graph, I can get 5 or the 6 channels on the screen at the same time, but the 6th channel (859.5875) I rarely ever see used for transmissions for some reason.

I am seeing the peak of the signal for the CC running today on 852.725. I see the transmissions on each of the other frequencies as they occur. When I get the muting, I see the entire transmission on SDR# and see nothing like a spike or other obvious anomalies... Any hints on what I should be looking for would be greatly appreciated!!

Thanks!

 

[jmulvihill]

If you set a filter to global it means that it uses whatever setting you have set for global in the profile. It's an easy way to set a filter from one place that will change filter settings on all sites and conventional departments that are set to global. Change the filter setting in the profile to different values to test and if you have a receive signal strenght of -80 or stronger, I.E. -70 -60, you could use the attenuator.

As the mute sometimes last for 10 second you could try and quickly change the squelch to 0 when the mute happens to see if you hear just noise or perhaps an interfering signal.

/Ubbe

I tried changing the squelch when the muting occurred, and it had no effect. The transmission stayed muted for the 5 seconds and then came back...

 

[UPMan]

From our engineer:

There is some latency for NOISE response, but it does not take 5 seconds.

I found a trace in the debug log that was falsely detected as digital.

I will release test firmware for this issue with some improvements and additional debug contents.

Have you seen any digital status icons such as LINK while muting?

 

[jmulvihill]

From our engineer:

There is some latency for NOISE response, but it does not take 5 seconds.

I found a trace in the debug log that was falsely detected as digital.

I will release test firmware for this issue with some improvements and additional debug contents.

Have you seen any digital status icons such as LINK while muting?

No, I have not noticed anything that would indicate a digital signal. I will go back and watch the videos to be sure, but can say 99.9% sure i have not. Would this digital detect mid transmission cause this behavior? For what it is worth, everything on this FL for Collin Cty is set to analog. There is one TG for Narc/Vice listed as DE, so I either have it avoided or omitted. I would have thought that once the transmission is locked on, that it is not attempting to decode again mid transmission until the mic is released and the delay time is up (2 sec in my config) before going back to ID Scanning. But that is just my attempt to guess what the code is doing from my programming experience and has zero basis in scanner software and control... ;-)

Let me know how I can assist in testing. I am happy to do whatever is needed.

Thanks! Have a great day!!

 

[KI5IRE]

I have noticed something similar on my SDS on multiple P25 systems. My SDS just cuts out in the middle of transmissions, regardless of location and antenna. When side by side my 436, my 436 has no issue but my SDS will mute and cut out. Also have noticed that my SDS has reception issues as well, will be right next to my 436 on the rubber duck, 436 shows signal, SDS won’t see any signal. Very frustrating.

 

[UPMan]

For EDACS, the conditions are very rare, so it could be an undetected bug. If the scanner detects what looks like a valid digital pattern, it will mute then spend some time trying to decode. This detection should be suppressed when channel mode is Analog, though. I'll make sure you get the test firmware (still being adjusted by engineering).

 

[jmulvihill]

Sounds good! Thanks so much!!

 

[UPMan]

Try the beta firmware and follow up in that thread: https://forums.radioreference.com/threads/sds100-sds200-v1-09-00-open-beta.385712/

 

[KI5IRE]

Anyone trying this update on P25 systems? I’ve been having issues with my SDS cutting in and out on P25 simulcast and single site systems. Anyone else having this issue?


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[KI6AOK]

Anyone trying this update on P25 systems? I’ve been having issues with my SDS cutting in and out on P25 simulcast and single site systems. Anyone else having this issue?


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The P25 simulcast I’m listening to does something similar (the audio breaks up and the NOISE readout spikes). Filters are minimally helpful.

 

[jjbond]

This is happening on analog non trunk channels as well, there’s a YouTube video comparing these units along side a $15.00 SDR dongle and the dongle winds hands down

 

[mule1075]

This is happening on analog non trunk channels as well, there’s a YouTube video comparing these units along side a $15.00 SDR dongle and the dongle winds hands down

Wins or Winds? And do you own either the 100 or 200? If you do cool and some experimentation needs to be done with filters etc. Again it has been stated time and time again if you do not need a solution for simulcast the xt series and hp series could potentially work better for what you need. Bottom line is if you want to buy the latest and greatest all good if what you are using now works then keep it. If you so choose bite the bullet and buy the sds series and try it out if it does not come up to the expectations you have sell it you will get almost all the cash back.

 

[jjbond]

Yes, sorry, wins hands down... (appears we don't have an edit button if we wait too long, thanks for letting me know). Here's the video I mentioned..

And here's an equally depressing video.... clearly the SDS has some work to do, hopefully this is just firmware...